1. Field of the Invention
The present invention relates to a resist composition preferably used in super-microlithography processes such as the manufacture of super LSI and high capacity microchips, and other photofabrication processes, and a pattern-forming method using the same. More specifically, the invention relates to a resist composition capable of forming a highly precise pattern with KrF excimer laser beams, electron beams, or EUV rays, and a pattern-forming method using the same, and further a resist composition suitable for fine processing of semiconductor devices with KrF excimer laser beams, electron beams, or EUV rays, and a pattern-forming method using the same.
2. Description of the Related Art
In the manufacturing process of semiconductor devices such as IC and LSI, fine processing by lithography using photoresist compositions has been conventionally carried out. In recent years, with the increment of integration of integrated circuits, hyperfine pattern formation of the levels of a sub-micron and a quarter-micron has come to be required. Under such a circumstance, the exposure wavelengths show a tendency to be shortening, such as from g-line to i-line, and further to KrF excimer laser beam. Further, lithography using electron beams, X-rays or EUV rays in addition to excimer laser beams has been developed nowadays.
Lithography using electron beams and EUV rays is taken as the pattern forming technique of the next generation or the next to the next generation, so that resists of high sensitivity and high resolution are required. The increase in sensitivity is a very important object in view of shortening of the processing time of wafers, but in positive resists for electron beams and EUV rays, pursuit of increment of sensitivity is accompanied by not only reduction of resolution but also deterioration of line width roughness (LWR), so that the development of a resist satisfying these characteristics at the same time is strongly desired. High sensitivity, high resolution, and good line width roughness are in relationship of trade-off, and how to satisfy these factors at the same time is a very important object.
In lithography using KrF excimer laser beams, it is also an important object to satisfy high sensitivity, high resolution, and good LWR at the same time. Further, line width variation (swing or SW) due to standing wave, shape, and variation of a resist film thickness in a high reflection substrate represented by ion implantation process is also a problem. It is known that the swing due to variation of a resist film thickness in a high reflection substrate is liable to increase when transmittance of a resist is high, and the swing is decreased by the introduction of a dye. However, reduction of resolution and deterioration of LWR are caused by the introduction of a dye, and further there are cases where the dye is sublimated and the baking plate is soiled at the time of baking in forming a resist film. How to satisfy these problems at the same time is very important.
As resists suitable for a lithographic process using KrF excimer laser beams, electron beams, or EUV rays, chemical amplification resists utilizing acid catalytic reaction are primarily used in view of the enhancement of sensitivity, and chemical amplification resist compositions mainly comprising a phenolic polymer having a property of being insoluble or hardly soluble in an alkali developing solution but becoming soluble in an alkali developing solution by the action of an acid (hereinafter referred to as a phenolic acid-decomposable resin) and an acid generator are effectively used in positive resists.
An initial chemical amplification positive resist composition comprising a resin protected with a photo-acid generator and an acid-decomposable group is disclosed in patent document 1 (U.S. Pat. No. 4,491,628). The chemical amplification positive resist composition is a pattern forming material capable of generating an acid at an exposed area upon irradiation with radiation such as far ultraviolet rays, and varying the solubility in a developing solution of the areas irradiated and not irradiated with actinic radiation to form a pattern on a substrate by the reaction with the generated acid as a catalyst.
Various kinds of positive resist compositions containing a resin protected with an acid-decomposable group are so far known. For example, a resist composition using a polyhydroxystyrene resin protected with an alkoxy (acetal) group is disclosed in patent document 2 (JP-A-5-249682 (the term “JP-A” as used herein refers to an “unexamined published Japanese patent application”)), a resist composition using a polyhydroxystyrene resin protected with different two kinds of acid-decomposable groups is disclosed in patent document 3 (JP-A-9-211866), a resist composition using a phenolic acid-decomposable resin copolymerized with an acid-decomposable acrylate monomer is disclosed in patent document 4 (U.S. Pat. No. 5,561,194), a polymer having a repeating unit capable of reducing the solubility of the polymer in an alkali developing solution such as methyl methacrylate and styrene is proposed in patent document 5 (Japanese Patent 3116751).
Patent document 6 (JP-A-2004-302434) discloses a resist composition using anthracene rings as a dye, and patent document 7 (JP-A-9-106073) discloses a resist composition using a nitrogen-containing polymer. However, high sensitivity, high resolution, and good LWR in a hyperfine area, and further, the swing due to standing wave, shape, and variation of a resist film thickness in a high reflection substrate represented by KrF ion implantation process have not been satisfied yet at the same time in every combination of these resist compositions in the present situation.